Ferric pyrophosphate. Fe6(P2O7)3. A salt containing ferric iron combined with the radical of pyrophosphoric acid.
Prep. By precipitating a solution of ferric sulphate with one of pyrophosphate of sodium, taking care to operate at a temperature below 59° Fahr.
Prop., &c. A gelatinous precipitate which dissolves with facility in excess of pyrophosphate of sodium. The citrate of ammonium is the most eligible solvent according to M. Robiquet, who first called attention to this salt as a remedial agent.—Dose, 5 to 10 gr.
Ferric Sulphate. Fe2(SO4)3. Syn. Persulphate of iron, Sulphate of sesquioxide of iron; Ferri persulphas, L. Prep. By adding to a solution of ferrous sulphate exactly half as much sulphuric acid as it already contains, raising the liquid to the boiling-point, and then dropping in nitric acid, until the liquid ceases to blacken by such addition. The solution evaporated to dryness furnishes a buff-coloured mass, slowly soluble in water.
Prop., &c. With the sulphates of ammonium and potassium it unites to form compounds to which the name ‘iron alums’ has been given. It forms the active ingredient in the ‘liquor oxysulphatis ferri’ of Mr Tyson, and is said by Dr Osborne to be a constituent of ‘Widow Welch’s pills.’ This salt is also formed when ferrous sulphate is calcined with free exposure to the air. Dissolved in water, it is used as a test for hydrocyanic, gallic, and tannic acids.
Ferric Sulphide. Syn. Persulphide of iron. This compound is prepared in the hydrated state (FERRI PERSULPHURETUM HYDRATUM) by adding, very gradually, a neutral solution of ferric sulphate to a dilute solution of potassium sulphide, and collecting, &c., the precipitate, as in the case of the hydrated ferrous sulphide. Proposed by Bouchardat and Sandras as a substitute for ferrous sulphide, to which they say it is preferable.
Ferric Tan′nate. Syn. Ferri tannas, Ferrum tannicum, L. Prep. From tannin, 1 part; boiling water, 150 parts; dissolve, add of freshly precipitated ferric hydrate (dried at 212° Fahr.), 9 parts; evaporate by a gentle heat to one half, filter, add of sugar 1 part, complete the evaporation, and at once put it into bottles.—Dose, 3 to 5 gr., thrice daily; in chlorosis, internal hæmorrhages, &c.
Double Ferric and Ammonium Tartrate. Syn. Ammonio tartrate of iron, Double tartrate of iron and ammonium; Ammonio
ferric tartrate, Ferri ammonio tartrate; Ferri ammonio tartras.
Prep. (Aikin.) Tartaric acid, 1 part; iron filings, 3 parts; digest in a sufficient quantity of hot water to barely cover the mixture for 2 or 3 days, observing to stir it frequently, and to add just enough water to allow the evolved gas to escape freely; next add ammonia, in slight excess, stir well, dilute with water, decant, wash the undissolved portion of iron, filter the mixed liquors, and evaporate to dryness; dissolve the residuum in water, add a little more ammonia, filter, and again gently evaporate to dryness, or to the consistence of a thick syrup, when it may be spread upon hot plates of glass or on earthenware dishes and dried in a stove-room, as directed for the corresponding citrate.